What you will need:
PenKnife x 1
Ruler x 1
Compressed Foam (I got mine from my hard disk packaging)
Step 1: The Foam
Cut the foam block into a long strip. I made mine slighter wider than my iPhone. The foam I am using is thick enough to make it quite stable.
Step 2: Making the Cuts
Basic cuts for the connector, cable and cutting a piece for propping the back. Be carefully not to cut through for the cut in the middle so as to maintain it as a single piece.
Step 3: Position It
After the cuts, take the cut away piece and place wedge it to the back as support. If you turn it to the slanted edge, you can prop your phone higher.
Step 4: All Done!
Now insert the cable and your iphone. For added stability, you may wish to use toothpicks thru the wedge piece into the main piece. Enjoy!